[clang] [llvm] [NVPTX] Change the alloca address space in NVPTXLowerAlloca (PR #154814)

[Artem Belevich via llvm-commits]

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@@ -502,3 +497,27 @@ void NVPTXPassConfig::addMachineSSAOptimization() {
   addPass(&PeepholeOptimizerLegacyID);
   printAndVerify("After codegen peephole optimization pass");
 }
+
+bool NVPTXTargetMachine::isCompatibleDataLayout(
+    const DataLayout &Candidate) const {
+  // XXX: Should we enforce that the Candidate DataLayout has the same address
+  // space for allocas?
+  if (DL == Candidate)
+    return true;
+
+  auto DLStr = DL.getStringRepresentation();
+  if (!StringRef(DLStr).contains("A"))
+    DLStr = DLStr.empty() ? "A" + std::to_string(ADDRESS_SPACE_LOCAL)
+                          : DLStr + "-A" + std::to_string(ADDRESS_SPACE_LOCAL);
+  auto NewDL = DataLayout(DLStr);
+
+  return NewDL == Candidate;
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Artem-B wrote:

So, the idea here is to effectively assume that if `Ax` is not explicitly specified in the data layout, we assume that the layout is compatible with `A5`. This contradicts LLVM spec which states that `A` `Defaults to the default address space of 0.`

I think we may be working around the problem here, instead of addressing the root cause.

https://github.com/llvm/llvm-project/pull/154814